The unique ability of the red blood cell to deform and withstand the high shear stress in the circulation is lost with altered molecular interactions in te membrane or changes in the cytosol. We have developed a novel technique Single Cell Micro-chamber Array or SiCMA, to rapidly analyze heterogeneous cell populations, and plan to show that this technology will allow the correlation of deformation and fragility with cell surface and cytosolic markers in heterogeneous populations of red blood cells. We propose a multidisciplinary approach with experts from mechanical engineering, cell biology, and clinical hematology to develop a novel technology for red cell membrane biology and show its applicability for clinical diagnosis of patients with hereditary spherocytosis (HS). To reach this goal we have formulated the following specific aims: 1) To optimize deformation measurements in SiCMA chambers, 2) To compare SiCMA deformation analysis with established technology, and 3.) To test the new technology on samples relevant for red cell pathology. Successful accomplishment will lead to the establishment of a novel approach to rapidly and highly cost-effective, select, define, and correlate cellular markers of individual cells in a heterogeneous re cell population, to be used in laboratory assessment of basic research in membrane biology as well as for prognosis and treatment of red cell disorders.